Roughing the passer

In gridiron football, roughing the passer refers to making contact with the passer (usually the quarterback) after the passer has released the ball from his hands. Touching the quarterback while he is in possession of the ball (attempting a quarterback sack) is a permitted act of defense. But once he releases the ball, defenders are not permitted to make contact with the quarterback unless carried to do so by momentum. Judgment over whether contact following release was the result of a violation or momentum is made by the referee on a case-by-case basis. If the defender then puts all of his weight on the passer at once he will also draw a penalty.[1]

Roughing the passer can also be called if the defender commits intimidating acts toward the passer, such as picking him up and stuffing him into the ground, or wrestling with him. It can also be called if the player who tackles the passer makes helmet to helmet contact.[2]

An exception to the roughing rule is where the quarterback rejoins a play after passing, such as in an attempt to block, recover a fumble, or tackle a defensive player who has gained possession of the ball. In this case, the quarterback is treated as any other player and may legally be contacted.